Compounding the oil majors' woes, the price of crude sunk below $70 in New York in early trading for the first time since the beginning of February on fears of a European sovereign debt crisis. Brent crude for July delivery slipped 92 cents, or 1.2pc, to $77.01 a barrel.

The vulnerable oil price will be bad news for BP, which is already facing up to $22bn (£15.2bn) of potential financial liabilities resulting from the spill.

It claims that the Minerals and Management Service failed to act on a whistleblower's warnings that a BP oil and gas platform in the Gulf of Mexico lacked safety and engineering documentation. The group wants BP to prove that one of the Gulf's largest oil rigs was built according to engineer-certified designs and is safe.

"We have reviewed the allegations made by Food and Water Watch (FWW) and have found no evidence to substantiate the organisation's claims with respect to Atlantis project documentation," a BP spokesman said.

Another body, the Center for Public Integrity, yesterday described the BP's safety record at its US refineries as the worst in the industry.

It claimed that two BP plants - at Texas City and Toledo - "account for 97pc of all flagrant violations found in the refining industry by government safety inspectors over the past three years".

BP claims to have cleaned up its act since its refinery in Texas City, exploded in March 2005, killing 15 workers, ploughing more than $1bn into improving the plan.

But data by the CPI found that BP received 862 citations between June 2007 and February 2010 for alleged violation.

The complaints come after a another environmental group, the Centre for Biological Diversity, said it was suing the US regulator for approving offshore drilling activities without regard to their impact on endangered marine species.

Separately, rival oil company Royal Dutch Shell will face a protest at its annual meeting by "ethical investors" against its oil sand developments in Canada. The investors are now concerned that if the US retreats from offshore exploration following BP's spill, it may rely more on tar sands drilling, using processes that emit more carbon dioxide than conventional extraction.